1. Field of Invention
The field of the currently claimed embodiments of this invention relates to systems and methods for processing ultrasound data, and more particularly to systems and methods for processing ultrasound data using dynamic programming procedures.
2. Discussion of Related Art
Ultrasound imaging is commonly used in detecting and targeting tumors, isolating organ structures, and monitoring invasive surgical procedures. One example of an intraoperative application of ultrasound involves its use in treating tumors. Such treatments include Electron Beam Radiation Therapy (EBRT) and hepatic tumor thermal ablation. A common challenge to these procedures is to accurately image the tumor so that the tumor can be treated most effectively while minimizing damage to the surrounding tissue. A further challenge encountered in such tumor therapies involves the ability to assess the state of the surrounding tissue after treatment or between treatments.
Conventional brightness (or B-mode) ultrasound has been used for intraoperative target imaging during thermal ablation procedures. However, B-mode ultrasound typically reveals only hyperechoic (i.e., brighter ultrasound signature) areas that result from microbubbles and outgassing from the ablated tissue. The tumor may be isoechoic, meaning that its brightness in ultrasound imagery is substantially indistinguishable from that of the surrounding tissue. In such cases, ablation effectiveness is estimated by the ultrasound-determined position of the ablation probe, and not by imagery of the tumor or surrounding tissue.
Ultrasound elasticity imaging has emerged as an effective technique to mitigate the disadvantages of B-mode ultrasound. Ultrasound elasticity imaging exploits the differences in mechanical properties of the tumor from those of the surrounding tissue medium. By imaging the deformation of the tissue in response to pressure exerted by the ultrasound probe, the contour of the tumor may be extracted from the surrounding tissue. In doing so, the ultrasound system generally tracks the deformation (or strain) of the tissue by tracking the motion of “speckle,” or coherent scattering features within the tissue.
Although an improvement over B-mode ultrasound, related art ultrasound elasticity imaging has limitations. First, related art image processing techniques result in artifacts and noise that degrade the quality of the image, and thus may impede effective target imaging. Second, related art image processing techniques are generally computationally expensive, which often results in significant lag times in image display. The artifacts and noise in related art ultrasound elasticity imagery generally results from speckle decorrelation due to speckle out-of-plane motion, and shadowing.
Another problem regarding related art ultrasound elasticity imaging is that the technician may easily apply too much pressure to the tissue surrounding the tumor. This exacerbates the problem of out-of-plane motion, because the surrounding tissue spreads out of the path (and thus out of the field of view) of the ultrasound probe. Further, applying too much pressure on the surrounding tissue may dislocate the tumor and temporarily alter its shape. Once the pressure is released, the tumor may return to its original location and shape. As such, the location and shape of the imaged tumor (when pressure is applied) may be different from the location and shape of the tumor in its “rest” state. The resulting inaccuracy in target imaging may result in inaccurate delivery of heat or radiation during treatment. Additionally, in the case of multiple treatments, because each technician may apply differing degrees of force, dislocation and distortion of the tumor may further degrade the precision of the determined location and size of the tumor.
Accordingly, there remains a need for improved systems and methods for processing ultrasound data.